So far the most commercially viable seat ventilation systems have been developed for front car seats. One of the reasons is that at least one of the front seats, specifically the driver seat, is always occupied. The driver is also typically the person who buys the vehicle. Another reason is the relative ease of front seat ventilation. That is, normally there is a space under the seat where the necessary air mover and its breathing passage may be arranged. Also, the seat back of a front seat normally has a three-dimensional metal frame for handling minor collision forces and more or less surplus space is available inside. It simplifies the system fitting. Such front vehicle seats may have two variants, i.e., with the ventilation or without the ventilation option, with the seat dimensions being the same in both cases.
In contrast, rear seats are typically left unventilated in many cars. The reason is that such seats are not “ventilation-friendly” in many cars. The typical rear seat construction is simply foam padding placed over an air impermeable base structure such as the vehicle profiled floor or the rear vehicle occupant compartment wall having an angled or inclined disposition. The foam thickness is minimal and adding an air mover and its breathing passage would require changing of the so called H-point, which is the seat surfaces designed locations. If the ventilation components are placed inside the bolsters, then the H-point may stay intact but the bolster cushioning function is reduced. In any event, rear seat ventilation causes safety concerns, and it is conventionally necessary to allow room for it in the very early stage of the vehicle design, before or during the time at which the body shape is determined.
Similar problems exist in furniture seating. For example, conventional seat ventilation systems are too bulky to be hidden in home or office style chairs.